The class Mammalia has three unique characteristics: hair, milk production in the mammary glands and three bones in the middle ear. Characteristics shared by other classes of animals include a warm-blooded metabolism, four-chambered heart and four limbs. Members of class Mammalia are called mammals.Know More
Most mammals give birth to live young; the exceptions to this are five species of egg-laying mammals called monotremes. The platypus and four species of echidna are the only living monotremes, as of 2014. Marsupials are a group of mammal species that give birth to less-developed live young that cannot survive away from the mother. Newborn marsupials continue to grow in an pouch outside of the mother's body. Kangaroos, koalas, opossums and wallabies are all examples of marsupials.
Mammals live on every continent and range in size from the 3-centimeter bumblebee bat to the 108-foot blue whale. They vary greatly in diet and habitat. There are herbivorous, carnivorous and omnivorous mammals, and mammals that live on land, underwater or both. Bats are the only mammals with the true ability to fly, but some other mammals glide between trees. Cetaceans, the group that includes dolphins and whales, are the only mammals that live exclusively underwater, but mammals such as seals and otters are able to move between land and water easily.Learn More
Characteristics of a Volvox include the fact that each cell contains two flagella, which aids in movement through water, and the colonies reproduce asexually. The cells of a Volvox are held together by protoplasm strands.Full Answer >
Sponges are extremely slow-moving or sessile filter-feeders that draw water through pores and specialized filter cells to gather food. Sponges are the most primitive type of animal in existence, featuring a cell-based organization where different cells have different tasks, but do not form tissues. All sponges live in the water, with a large majority of species living in the oceans.Full Answer >
Gymnosperms lack the bright, showy flowers and fruit-covered seeds of angiosperms. Gymnosperm literally means “naked seed,” and they are more primitive plants than angiosperms are. Gymnosperms evolved about 300 million years ago.Full Answer >
Members of Monera, which include the prokaryotic bacteria and cyanobacteria, are single-celled and lack a membrane-bound nucleus. They also lack other membrane-bound organelles, such as mitochondria, and reproduce asexually.Full Answer >